1. Field of the Invention
Forming a borehole transversely of a highway necessitates that the boring tool be capable of being angled downwardly at one side of the highway and then turned in an upward direction while beneath the highway to emerge through the surface of the earth on the opposite side of the highway. This boring tool is capable of accomplishing this function.
2. Description of the Prior Art
U.S. Pat. No. 5,002,138 issued Mar. 26, 1991 and U.S. Pat. No. 5,078,218 issued Jan. 7, 1992 to Smet for STEERABLE DRILLING MOLE both disclose a down hole motor connected with a steering element in turn obliquely connected with a drill head driven by a drilling motor. The motors has a part spherical ball at its rearward end in a guide socket by operating the motor and turning the guide element the motor and the drill bit is disposed in a desired upward or lateral direction monitored as indicated by a monitoring device rearwardly of the motor.
U.S. Pat. No. 4,453,603 issued Jun. 12, 1984 to Voss et al for APPARATUS AND METHOD FOR SELECTED PATH DRILLING and U.S. Pat. No. 4,993,503 issued Feb. 19, 1991 to Fisher et al for HORIZONTAL BORING APPARATUS AND METHOD illustrate the general state-of-the-art. The Voss patent disclosing hydraulic rams moving a hole forming apparatus under an obstruction with the small hole later enlarged as by reaming for installing wiring or optical cable in which the hole may be cased by a pipe forced into the large borehole. The Fisher patent discloses a boring apparatus having an angle cutting head which by its rotation forms a borehole substantially larger than the drill string connected with a cutting head. When it is desired to change the direction of the borehole the rotation of the drill string is stopped and the drill bit is forced into the soil and utilizes a jet stream which starts a hole at an angle to the previously drilled borehole.
This invention is believed distinctive over the above patents by mounting a drill head between cooperating pairs of longitudinally spaced tapered surface wedges concentrically supporting a drill bit on a drill string subjoint within a casing moved forwardly in response to the hole forming action of the drill bit. The drill bit may be oriented in an upward direction by interrupting forward movement of the casing and moving the drill string and drill bit forwardly relative to the casing in which moveable wedges moving longitudinally relative to stationary wedges tilts the forward end of the drilling head in an upwardly inclined direction.